aeriel position
- Thread starter jjb1333
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Depends how near the transmitter is and whether you've got the correct aerial for it. Old analogue technique was to have an assistant sat by the telly shouting instructions. Digital- get to setup screen, look for signal strength and quality. Much easier to have the telly up by the aerial (which is not impossible these days)
Strength is how many microvolts are being induced in your aerial. Quality could be either how good the separation between 1 and 0 is OR it could be the percentage of packets with matching checksums. IF you're getting all channels available and there aren't great lumps of artifacts across the screen then probably leave well alone- chimneys are dangerous things to work up.
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There's an arc in which you'll get enough signal to make a picture. The closer the aerial gets to the optimum direction within that arc then the greater the signal Strength (its power) and as a result of that then the larger the difference between the signal and any background noise which is what we call signal to noise ratio, this is what's measured by the Quality reading. If you have 90% quality then that suggests to me that you're in quite a strong signal area.
Quality is important because it only ever reduces after the aerial. Each joint, piece of cable or item of receiving equipment has the potential to introduce noise. More noise equals a lower signal to noise ratio. Any sort of amplifier can boost the signal power but it will also amplify the existing noise in the signal too, and it will add its own noise too. The nett result is a more powerful signal but with worse Quality. There's no piece of equipment a consumer can add then that will improve signal Quality. Once it is gone it is gone.
Strength is a measure of the signal power but it also includes any background noise. It's important because the power of the signal diminishes as it passes through cable and other passive devices such as unpowered splitters due to electrical resistance. As you have seen from your own measurements, you don't need a lot of power to have a usable signal.
When aligning an aerial the size of the reception arc is determined by the field strength of the signal where you live and the sensitivity of the aerial. In very general terms the field strength is affected by the power of the transmitter, your distance from that transmitter, the geography of the land and surrounding buildings. Occassionally there will be competing signals from ajacent transmitters to factor in too.
The aerial sensitivity is governed by the type and quality of the aerial and its 'tuning' (the gain curve). What that means is that an aerial might be exellent at receiving frequencies in the upper end of the signal band (this is your typical High Gain Wideband aerial) but if your local transmitter sends out all the channels at the lower end of the range then your aerial won't work as well as one with either a flatter gain curve ( a Log Periodic) or one optimised for your local transmitter such as say a Group A Yagi if that's appropriate. The less suited the aerial is then the narrower the arc and the lower power it will produce.
Quality is important because it only ever reduces after the aerial. Each joint, piece of cable or item of receiving equipment has the potential to introduce noise. More noise equals a lower signal to noise ratio. Any sort of amplifier can boost the signal power but it will also amplify the existing noise in the signal too, and it will add its own noise too. The nett result is a more powerful signal but with worse Quality. There's no piece of equipment a consumer can add then that will improve signal Quality. Once it is gone it is gone.
Strength is a measure of the signal power but it also includes any background noise. It's important because the power of the signal diminishes as it passes through cable and other passive devices such as unpowered splitters due to electrical resistance. As you have seen from your own measurements, you don't need a lot of power to have a usable signal.
When aligning an aerial the size of the reception arc is determined by the field strength of the signal where you live and the sensitivity of the aerial. In very general terms the field strength is affected by the power of the transmitter, your distance from that transmitter, the geography of the land and surrounding buildings. Occassionally there will be competing signals from ajacent transmitters to factor in too.
The aerial sensitivity is governed by the type and quality of the aerial and its 'tuning' (the gain curve). What that means is that an aerial might be exellent at receiving frequencies in the upper end of the signal band (this is your typical High Gain Wideband aerial) but if your local transmitter sends out all the channels at the lower end of the range then your aerial won't work as well as one with either a flatter gain curve ( a Log Periodic) or one optimised for your local transmitter such as say a Group A Yagi if that's appropriate. The less suited the aerial is then the narrower the arc and the lower power it will produce.
One more point: If the installation is poorly done, you can end up in a situation where you lose the signal in bad weather.
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